The field of the invention is that of turbine engines, and in particular that of turbine engine fan blades made of composite material having leading edges that include structural reinforcement made of metal, and the present invention relates more particularly to a method of high temperature forging metal parts, such as for example metal structural reinforcement for the leading edge of a composite turbine engine blade.
Nevertheless, the invention is also applicable to making any part of complex geometrical shape and to making metal reinforcement for reinforcing a leading edge or a trailing edge of a blade in any type of turbine engine, whether for terrestrial or aviation use, and in particular in a helicopter turboshaft engine or in an airplane turbojet.
It is known to fit turbine engine fan blades that are made of composite materials with metal structural reinforcement extending over the full height of the blade and extending beyond their leading edges, as mentioned in Document EP 1 908 919 filed in the name of the Applicant. Such reinforcement makes it possible to protect the composite blade in the event of the fan receiving an impact from a foreign body, such as for example a bird, hail, or indeed grit.
In particular, the metal structural reinforcement protects the leading edge of the composite blade by avoiding any risk of delamination, of fiber rupture, or indeed of damage by loss of cohesion between fibers and the matrix. In known manner, it may be made either entirely by milling from a titanium block, which requires numerous finishing operations and complex tooling involving major manufacturing costs, or else from a preform obtained from a simple metal bar and a succession of forging steps, as described in particular in French application FR 2 961 866 filed in the name of the Applicant.
Such forging steps are nevertheless particularly complex as a result of the three-dimensional nature of the desired deformations. That is why the Applicant has developed tooling in its patent application FR 2 965 496 for hot-shaping that is referred to as “multi-effect” tooling since it makes it possible to perform deformation in three-dimensional manner (i.e. in different directions simultaneously) by means of a single-acting press (i.e. having only one working axis) that is inexpensive and under high temperature conditions, i.e. temperatures higher than 850° C. (about 940° C. for making titanium reinforcement).
Although that method generally gives satisfaction in terms of its rapidity and its simplicity, it nevertheless presents certain drawbacks at the end of the operation as a result of angular twist undercuts that exist all along the part that is to be made and that require dislodging movements to be performed in several directions, which can be a source of defects in the part.